A Comprehensive Guide to IBM WebSphere Host Publisher Version 3.5

Chapter 17. EJB application support 507

17.2.2 Host Publisher and EJB applications

Host Publisher Version 3.5 provides EJB application support and has the

following main characteristics:

1. It provides the Host Publisher EJB (HPubEJB) capable of running any Host

Publisher Integration Object.

2. A new option has been added to Host Publisher Studio to generate EJB

support files (including the EJB Access Bean) for an Integration Object.

Host Publisher EJB

The Host Publisher EJB is provided by Host Publisher Server (runtime) and has

the following characteristics.

1. It is automatically installed in the Default Container of the Host Publisher

application server.

2. It is capable of running any Database or Host Access Integration Object

(except Express Logon Integration Objects).

3. The lifecycle of an EJB instance corresponds to an Integration Object chain

(stateful EJB).

4. A single EJB is a good choice for resource efficiency:

EJB containers usually run only a small number of unique EJBs, but a large

number of EJB instances.

Host Publisher Studio: EJB support

The following components are generated in addition to the Integration Object

when this option is chosen in Host Publisher Studio:

1. An EJB Access Bean (EJB client code) is generated with the same signature

as the corresponding Integration Object.

2. The Integration Object properties object is used to pass input properties to

the Host Publisher EJB (HPubEJB), and to pass resulting output properties

back to the Access Bean.

3. The Helper object extends the Integration Object (IO), generated for

processing efficiency.

508 IBM WebSphere Host Publisher Version 3.5

Figure 17-2 Executing Host Publisher EJB in a Web container

EJB Access Bean

The main characteristics of the EJB Access Bean are:

򐂰 It is generated when the Host Publisher Studio option is selected for each

Integration Object.

򐂰 The EJB Access Bean is invoked by clients (servlet/jsp/java

application/custom EJB).

򐂰 It has a similar signature to the corresponding Integration Object (IO),

allowing any client to interact with the EJB Access Bean like it would with the

IO itself.

򐂰 Clients call Access Bean’s setter methods to set IO input properties.

򐂰 Clients calls Access Bean’s execution method.

– do HPTransaction (from jsp/servlet -within Web environment)

– processRequest (form application/custom EJB - outside of the Web

environment)

򐂰 If the corresponding IO is non-chained or first in chain, Host Access IO:

EJB Access Bean retrieves parameters from its properties file:

– network location of JNDI server.

– name of Host Publisher EJB (HPubEJB).

򐂰 The Access Bean does a JNDI lookup to locate deployed Host Publisher EJB

(HPubEJB).

򐂰 The Access Bean (EJB client) remotely creates an instance of HPubEJB.